Thermoformed cover for electronic device and method for forming

ABSTRACT

A thermoformed cover and related method for forming the thermoformed cover for an electronic device including at least one body element is made from a thermoplastic sheet having characteristics and properties to accommodate the mechanical requirements of the cover for the electronic device. The thermoplastic sheet has characteristics such that when the thermoplastic sheet is heated to a suitable temperature, the thermoplastic sheet becomes pliable and stretchable. At least a portion of the heated thermoplastic sheet is made to conform by vacuum, pressure or other suitable means to a mold arranged to substantially correspond to the desired cover for the electronic device. A thermoformed cover corresponding to the desired cover for the electronic device is formed in at least a portion of the thermoplastic sheet and the thermoformed cover is cut away or otherwise separated from the thermoplastic sheet. The thermoformed integrated cover may be arranged to replace or to envelop the cover of the electronic device or may be arranged as a protective insert cover between the body element and the cover of the electronic device.

TECHNICAL FIELD

The present invention relates generally to thermoforming and deals more specifically with thermoformed articles such as covers for portable electronic devices and more particularly, though not necessarily, with integrated thermoformed covers for handheld portable electronic devices including mobile telephone devices.

BACKGROUND OF THE INVENTION

Portable electronic devices, particularly handheld portable electronic devices, are becoming increasingly popular and are rapidly expanding in use and function. Such portable electronic devices include for example, mobile telephone communication devices, gaming devices, music players, PDA's and the like. As technology continues to change, additional features and functions are provided by manufacturers and designers in an attempt to satisfy consumer demand and gain a competitive advantage. The seemingly endless competitive cycle of product launches and technology advertising hype has caused manufacturers and designers to search for ways to produce and introduce new products for maximum consumer impact while at the same time utilizing minimum effort for concepts and designs.

The covers or enclosures for these changing and new introduction products are constantly being designed to accommodate both mechanical and appearance requirements. As the time duration between new product introductions shortens and additional demands are made to accommodate multiple decorative and graphic cover appearances, it will be necessary to also shorten the time to production and to reduce the cost of producing the covers to maintain profitability because the cost will be amortized over a shorter product lifetime and presumably a lower number of total products produced.

It is known in the prior art to use injection molding techniques and processes to manufacture covers for portable electronic devices such as mobile telephones because it is possible to consistently obtain good mechanical parts with reasonable tolerances. In a typical injection molding system, raw material granulates, generally a polymer or other suitable plastic formulation, are melted and injected into a mold to obtain the desired shape and mechanical functions of the cover. Injection molding systems and methods for producing molded parts are well known and understood to those skilled in the art and are not discussed in detail herein. Injection molding is typically used and well suited for producing a high number of parts because the tooling costs and molds can be amortized over such a large number of parts produced. The reader is referred to the literature and numerous texts for further details and explanation to gain a further understanding of injection molding systems and methods and the economies obtainable when using injection molding for producing a high number of parts.

In one prior art typical mobile telephone enclosure, the mobile telephone has two covers, a front half and a rear half referred to respectively as A- and B-covers. The front enclosure portion generally has an opening or aperture to allow the screen display to be viewed. The screen opening in the front half enclosure is covered with a window and a bezel surrounding the opening to safeguard the screen display and to seal the window to the enclosure. Additional openings or apertures are provided in the front enclosure to receive and accommodate various keys or buttons arranged to carry out intended functions of the mobile telephone device for example, dialing a phone number, selecting a desired function and other well known operations of the device. The keys may be individual keys or keys carried on a keymat. The mold for such covers is complex and the cover is made up of a number of individual components. Colors, graphics and patterns are usually then applied to the front enclosure portion and user-interface text/graphics is applied to the key locations on the separate keymat. The front enclosure portion and the keymat are then assembled in conjunction with the various window components and the bezel components to create the finished front cover sub-assembly. The front and rear enclosure portions are joined together to form the enclosure for the electronic circuitry, battery supply, screen display and various components as necessary to carry out the intended functions of the mobile telephone. Although described as front and rear enclosure portions above, the portions comprising the enclosure may be any desired shape to define the enclosure.

One major disadvantage associated with injection molding the covers is that complicated molds are needed and which molds have long lead times to manufacture. Therefore, injection molding set-up time requirements are not satisfactory to achieve the desired shorten times between new product introductions to manufacture and produce the device covers.

A further disadvantage and shortcoming of injection molding techniques is that each part forming the enclosure, i.e., for example, the cover halves and window portion components, requires its own individual mold.

It is also known to use thermoforming to mold plastic parts. Thermoforming is a much more simpler process compared to injection molding because the raw material is a film rather than a melted plastic which has to flow during the melt stage for injection into the mold. Thermoforming is most commonly used to mass produce parts for the packaging industry. In thermoforming, a plastic film or sheet having a thickness in the range of about 0.1-2.0 mm is formed by pressure and heat. Next, the film is then heated to a point where it is softened but not melted and then the film is transferred to a mold where pressure and vacuum is used to transfer the film to the mold to shape the film in the form of the desired object or article as defined by the shape of the mold. It is possible with thermoforming to produce deep 3D parts however, due to the simple mold technology that is used, it is not possible to get rips or complicated mechanical functions into the part.

An advantage of thermoforming is the cost of a thermoformed mold is substantially less than a mold used in injection molding and therefore thermoforming is better suited and more economical for producing lower numbers of parts compared to injection molding.

A further advantage is the yield in thermoformed produced products is much better than in injection molded products because the raw material is film and there is no need for drying, transporting and melting plastic granules as required in injection molding.

It would be desirable therefore to provide a cover for an electronic device and a method to produce the cover that overcomes the disadvantages associated with injection molding techniques and processes for producing covers for electronic devices by utilizing thermoforming processes to produce the covers.

A yet further advantage is products or articles made by thermoforming require less machine set-up time compared to injection molding machine set-up time.

A still further benefit is molds used in thermoforming are lower cost compared to molds used in injection molding therefore making low numbers of parts production runs cost effective.

A further benefit is prototyping new products or modifying existing products is relatively inexpensive using thermoforming processes compared to injection molding processes.

It is an object of the present invention therefore to provide a thermoformed cover for an electronic device in which the cover parts are easily produced in a short turn around time.

SUMMARY OF THE INVENTION

In accordance with a broad aspect of the invention, a thermoformed cover and related method for forming the thermoformed cover is presented. In one embodiment, an integrated cover for an electronic device including at least one body element for carrying suitable electronic circuitry to control and carry out the intended operational functions of the electronic device is made from a thermoplastic sheet having characteristics and properties to accommodate the mechanical requirements of the cover for the electronic device. The thermoplastic sheet has characteristics such that when the thermoplastic sheet is heated to a suitable temperature, the thermoplastic sheet becomes pliable and stretchable. At least a portion of the heated thermoplastic sheet is made to conform by vacuum, pressure or other suitable means to a mold arranged to substantially correspond to the desired cover for the electronic device. A thermoformed cover corresponding to the desired cover for the electronic device is formed in at least a portion of the thermoplastic sheet and the thermoformed cover is cut away or otherwise separated from the thermoplastic sheet. The thermoformed integrated cover may be arranged to replace or to envelop the cover of the electronic device or may be arranged as a protective insert cover between the body element and the cover of the electronic device.

In a further embodiment of the invention a method is provided for thermoforming a cover for an electronic device having at least one body element and includes providing a thermoplastic sheet and a suitable mold arranged to substantially correspond to the desired cover for the electronic device. The thermoplastic sheet is heated to a suitable temperature and at least a portion is conformed to the mold by vacuum, pressure or other means. The heated thermoplastic sheet is cooled and removed from the mold and the thermoformed cover formed therein is cut away or otherwise separated from the thermoplastic sheet. The surface of the thermoplastic sheet may be silk screen printed with desired text, graphics, patterns and the like prior to the heating of the thermoplastic sheet such that the text, graphics, patterns and the like appear on the outer facing surface of the thermoformed cover.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional features, benefits and advantages of the present invention will become readily apparent from the following written description taken in conjunction with the drawings wherein:

FIGS. 1A-1E present a schematic representation of the major functional operations to produce a thermoformed cover embodying the present invention;

FIGS. 2A-2B present a schematic representation of alternate major functional operations to produce a thermoformed cover embodying the present invention;

FIG. 3A is a schematic representation of a thermoplastic sheet used to produce a thermoformed cover embodying the present invention showing a silk screen printed window border on the exterior outward facing surface of the thermoplastic sheet;

FIG. 3B is a schematic representation of a thermoformed cover embodying the present invention showing the silk screen printed window border of FIG. 3A on the exterior outward facing surface of the thermoformed cover;

FIG. 4A is a schematic representation of a thermoplastic sheet used to produce a thermoformed cover embodying the present invention showing a silk screen printed window border and keymat on the exterior outward facing surface of the thermoplastic sheet;

FIG. 4B is a schematic representation of a thermoformed cover embodying the present invention showing the silk screen printed window border and silk screen printed keymat of FIG. 4A on the exterior outward facing surface of the thermoformed cover;

FIG. 5 is an exploded view schematic representation of a laminate made up of a keypad sandwiched between two thermoplastic sheets;

FIG. 6 is a schematic representation of a laminate made up of a keypad sandwiched between two thermoplastic sheets including an integral connector adaptor for connecting the thermoformed cover embodying the present invention to an electronic device such as a mobile telephone;

FIG. 7 is a block diagram showing the major functional operations in a system for producing a thermoformed cover embodying the present invention.

FIG. 8 is a schematic exploded view representation of a decorative thermoformed cover embodying the present invention arranged to envelop the cover of a mobile telephone.

FIG. 9 is a schematic exploded view representation of a protective insert thermoformed cover between the body element and the cover of a mobile telephone.

FIG. 10 is a flowchart showing the major functional steps for making a thermoformed cover in accordance with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now to the drawings and considering the invention in further detail, the process of thermoforming a product or article, such as for example, a cover for an electronic device including a mobile telephone, involves heating a flat sheet of a suitable thermoplastic material until the sheet is pliable and stretchable, and then forcing the hot sheet against the contours of the surface of a mold having the desired article shape and size by using vacuum, pressure, mechanical means, blow molding or any combination thereof. The heated thermoplastic sheet is held to the shape of the mold by atmospheric pressure and after it is allowed to cool, the thus formed thermoplastic sheet retains the shape and detail of the mold.

The plastic materials used for thermoforming must have sufficient hot melt strength to support themselves during the thermoforming process. Typical thermoplastic materials include but are not limited to acrylic, ABS, polyesters, PVC, polystyrene, polycarbonate, polyethylene and polypropylene. Each thermoplastic material has its own unique set of properties which may be modified to achieve the desired mechanical properties and characteristics to accommodate the requirements of the particular article or product to be produced, for example, the cover of an electronic device such as a mobile telephone.

In general, thermoplastic sheets used for thermoforming are produced by a process of extrusion in which polymer resin pellets for example, are heated to the melting point. The melted polymer resin is then forced through a die to form a sheet. Multi-layered thermoplastic sheets may also be produced by a process of co-extrusion wherein multiple layers of similar polymers are co-extruded over one another to produce a laminated thermoplastic sheet.

Cut sheet thermoforming machines which are well known to those skilled in the art, may also be used to form the thermoplastic sheets. The details of such cut sheet thermoforming machines are not essential to gain an understanding of the present invention. The reader is referred to trade journals, textbooks and other applicable literature for a further explanation of the details of cut sheet thermoforming machines.

Turning to FIGS. 1A-1F, a schematic representation of the major functional operations to produce a thermoformed cover is shown therein for purposes of providing an explanation of the present invention. It will be recognized by those skilled in the art that the present invention may be practised to thermoform any desired article or product other than covers for a mobile telephone. For example, the thermoformed cover embodying the invention may be formed for a gaming device, music player, PDA and other well known electrical devices.

In FIG. 1A, a flat sheet generally designated 10 of a thermoplastic material having a suitable makeup or composition to achieve the intended desired characteristics is provided at the beginning or first stage of the thermoforming process. The thermoplastic sheet 10, often commonly referred to as a plastic film, has a thickness in the range of about 0.4 to 1.0 millimeters depending upon the mechanical requirements of the covers for the electronic device.

The thermoplastic sheet 10 is moved into position over a mold body generally designated 20 in FIG. 1B. The mold body 20 carries an embossed mold 22 on its surface 24 wherein the body 22 has the desired shape, size and contours of the cover to be thermoformed. The thermoplastic sheet 10 is drawn down over the embossed mold 22 by means of vacuum, or air pressure, mechanical means or any other suitable means well known to those skilled in the art of thermoforming to carry out the intended function. As illustrated in FIG. 1C, the thermoplastic sheet is drawn down such that the thermoplastic sheet 10 is held to the exterior surface shape of the embossed mold 22 wherein the portion of the thermoplastic sheet 10 held against the exterior surface shape of the embossed mold 22 becomes the cover and is generally designated 30. The thermoplastic sheet 10 retains the shape and detail of the embossed mold 22 and after cooling the thermoformed thermoplastic sheet is removed from the mold body 20 and the embossed mold 22 as illustrated in FIG. 1D. The thermoformed cover 30 is next cut away from the thermoplastic sheet 10 as illustrated in FIG. 1E to separate or otherwise remove the thermoformed cover 30 from the thermoplastic sheet 10. The thermoformed cover 30 may be an outer front or top cover, or an outer rear or bottom cover, an overlay cover for the outer front cover or outer rear cover and further may have any desired configuration to accommodate the electronic device with which the thermoformed cover is used.

It will be recognized and appreciated that a cover may be made up of a number of portions or segments that fit together to define the cover. Accordingly, the term “cover” as used herein contemplates all shapes, sizes, configurations and features to achieve the intended function.

Turning now to FIGS. 2A-2B, an alternate embodiment of major functional operations to produce a thermoformed cover is shown therein in a schematic representation for purposes of providing an explanation of the present invention. A flat sheet of a suitable thermoplastic material such as the sheet 10 described above in connection with FIG. 1A is provided at the beginning or first stage of the thermoforming process. The thermoplastic sheet 10 is moved into position over a mold body generally designated 40 in FIG. 2B in which a mold cavity generally designated 42 is formed in the surface 44 of the mold body 40. The mold cavity 42 has the desired shape, size and contours of the cover to be made by thermoforming. The heated thermoplastic sheet 10 is drawn down into the cavity 42 by means of vacuum, pressure, mechanical or other suitable means to carry out the intended function. The heated thermoplastic sheet 10 is drawn into the mold cavity 42 and against the surface contours of the mold formed and defined by the mold cavity 42 in the mold body 40 therein. The thermoplastic sheet is allowed to cool and is removed from the mold body 40. The portion of the thermoformed thermoplastic sheet drawn into the mold cavity 42 retains the shape and detail of the mold cavity 42. The thermoformed cover is then trimmed or cut away from the thermoplastic sheet 10 in a similar manner as described above in connection with FIGS. 1A-1E to separate the thermoformed cover from the thermoplastic sheet.

Turning now to FIGS. 3A and 3B, the present invention provides additional cost savings and a shortened time to produce a thermoformed article such as for example, a cover for a mobile telephone can be realized by silkscreen printing a border or window frame generally designated 50 directly on the surface 52 of a transparent or clear thermoplastic sheet generally designated 60. The window border 50 is silkscreen printed such that the final thermoformed cover locates the window border in registration with the display screen 51 carried by the mobile telephone as illustrated in FIG. 3B. In a similar manner as shown in FIGS. 3A and 3B, in addition to the window border 50 being silk screen printed on the surface 52 of the clear thermoplastic sheet 60, FIGS. 4A and 4B show that keys 54, 54 may likewise be silkscreen printed on the surface 52 in a desired arrangement 56 corresponding to the placement of keys on the mobile telephone to carryout the intended function. The location of the silkscreen printed border 50 and keys 54, 54 on the surface 52 of the thermoplastic sheet 60 is such that after thermoforming the cover, the window border 50 and keys 54, 54 of the key arrangement 56 are in proper registration with the screen display 53 and keypad (not shown in FIG. 4B) carried by the mobile telephone device as illustrated in FIG. 4B. In addition to the window border 50 and keys 54,54, graphics, text or other indicia may also be silkscreen printed on the surface 52 prior to the thermoforming of the cover.

In a further embodiment of the present invention, a thermoformed cover has an integrated keypad with the cover by forming a laminate as schematically represented in exploded view in FIG. 5 by sandwiching the keypad between two thermoplastic sheets. A keypad or keymat generally designated 70 is suitably arranged and carried by a first thermoplastic sheet 72. A second thermoplastic sheet 74 overlies the keypad 70 and the first thermoplastic sheet 72 to form a laminated thermoplastic sheet with the keypad with the keypad sandwiched between the thermoplastic sheets 72, 74. The laminated thermoplastic sheet may be formed using a co-extrusion process or other suitable process well known to those skilled in the art. The laminated thermoplastic sheet is used to produce the thermoformed cover in a similar manner as described above in connection with FIGS. 1A-1E, 2A and 2B.

Turning now to FIG. 6, a schematic representation of a laminated keypad thermoplastic sheet is shown therein and generally designated 80. A connector adaptor generally designated 82 is also sandwiched between the thermoplastic sheets and provides the appropriate electrical connections between the mobile telephone and the thermoformed cover with which the mobile telephone is used. The connector 82 is located such that the connector is in registration with the corresponding mating connector in the mobile telephone when the thermoformed cover is used with the mobile telephone. Silkscreen printing of the window border and the keys of the keypad arrangement may also be utilized as discussed above.

Turning now to FIG. 7, a block diagram showing the major functional operations in a system for producing a thermoformed article, such as a cover for a mobile telephone is illustrated therein and generally designated 100. The first major functional operation shows a sheet extrusion station generally designated 102 and contemplates providing a suitable thermoplastic sheet having the desired properties and characteristics in accordance with the thermoformed article requirements. The sheet extrusion station 102 is itself not essential to the invention because if desired, the thermoplastic sheet may be provided by any suitable means known to those skilled in the art, however it is included herein for the sake of completeness. The thermoplastic sheet, which may be a single layer or multiple layers co-extruded as a laminated thermoplastic sheet is next advanced to a silkscreen printing station generally designated 104 to for example, in the case of a mobile telephone cover, receive a display screen window border, keymat arrangement, graphics or other indicia printed on the surface of the thermoplastic sheet as desired in accordance with the intended function of the mobile telephone. An optional graphic printing station generally designated 106 may also be utilized to provide additional text, graphics, decoration or the like to the surface of the thermoplastic sheet however, it is generally contemplated that all text, graphics, decorations and the like will be applied at substantially the same time at the silkscreen printing station 104. The silkscreen printed thermoplastic sheet is next advanced to the thermoforming station generally designated 108 for thermoforming to conform the thermoplastic sheet to the shape and contours of the mold at the thermoforming station to form the desired thermoformed cover. The thermoplastic sheet is cooled, removed from the mold and then moved to the trimming station generally designated 110. The cover is trimmed or otherwise or separated removed from the thermoplastic sheet to yield the desired thermoformed cover. The thus removed thermoformed cover is collected at the cover collection station generally designated 112.

Although it is contemplated that the thermoformed cover embodying the present invention may be used in place of an existing cover of an electronic device, such as a mobile telephone, the thermoformed cover may also be fitted directly over the existing cover of the mobile telephone in a glove-like fashion as illustrated schematically in FIG. 8. As schematically shown in FIG. 8, a thermoformed cover 120 is arranged to envelop the front cover 122 of a mobile telephone 124. The thermoformed cover 120 is silk screen printed with desired decorations 126, 128 on the surface 130. A decorative border 132 may likewise be screen printed around the display screen window 134. Thus, a new decorative cover having different indicia, graphics or text including color from the existing cover of the mobile telephone may be made and used with an existing mobile telephone without incurring the substantial additional cost of a new traditional mobile telephone cover having the desired text, indicia, graphics or color.

In a further embodiment as schematically illustrated in FIG. 9, a thermoformed cover 140 is arranged as a protective insert cover between the body element 142 and the inside facing portion 144 of the cover 146 of the electronic device 148. The thermoplastic sheet used to thermoform the insert 140 is selected to be sufficiently thin to easily fit between the body element 142 and the cover 146. The thermoformed cover 140 may be used to provide protection for the user interface for example in the case of a mobile telephone. The thermoformed cover 140 may include an appropriately dimensioned window in registration with the window 150 in the cover 146 or may be clear to allow the user to see information shown on the display screen 152.

Although the invention has been described above showing a single article being thermoformed at a time, it is contemplated that multiple articles for example, the front and rear covers of a mobile telephone, or multiples of the front and rear covers may be thermoformed at the same time on the same mold body providing further additional cost savings and shortening the turnaround time for production of the covers.

Turning now to FIG. 10, a flowchart showing the major functional steps for thermoforming a cover in accordance with the method of the present invention is shown therein and generally designated 200. The method starts with step 202 by providing a suitable thermoplastic sheet as discussed above. Next, a suitable mold corresponding to the desired cover is provided in step 204. The thermoplastic sheet is next heated to a suitable temperature in step 206 to make the thermoplastic sheet stretchable and pliable. The heated thermoplastic sheet is conformed to the mold by means of vacuum, pressure or other suitable means in step 208. The conformed heated thermoplastic sheet is cooled and removed from the mold in step 210. Next, the thermoformed cover is removed from the thermoplastic sheet by cutting or other suitable means in step 212. An optional silk screen printing operation can be performed in step 214 between steps 204 and 206 to silk screen print desired text, graphics, patterns and the like to the surface of the thermoplastic sheet such that the text, graphics, patterns and the like appear on the outward facing surface of the thermoformed cover.

It will be recognized by those skilled in the art that alternate and additional steps may be used for thermoforming a cover in accordance with the invention. Therefore, the invention is described by way of example rather than limitation. 

1. An integrated cover for an electronic device including at least one body element for carrying suitable electronic circuitry to control and carry out the intended operational functions of the electronic device, said cover comprising: a thermoplastic sheet having characteristics and properties to accommodate the mechanical requirements of the cover for the electronic device; said thermoplastic sheet further having characteristics such that when said thermoplastic sheet is heated to a suitable temperature, said thermoplastic sheet becomes pliable and stretchable wherein at least a portion of said heated thermoplastic sheet conforms to a mold arranged to substantially correspond to the desired cover for the electronic device; and whereby a thermoformed cover corresponding to said desired cover for the electronic device is formed in said at least a portion of said thermoplastic sheet.
 2. The integrated cover for an electronic device as defined in claim 1 further comprising said thermoformed cover being cut away from said at least one portion of said thermoplastic sheet.
 3. The integrated cover as defined in claim 2 further being arranged for replacing the cover of the electronic device.
 4. The integrated cover as defined in claim 2 further being arranged to envelop the cover of the electronic device.
 5. The integrated cover as defined in claim 2 further being arranged as a protective insert cover between the body element and the cover of the electronic device.
 6. The integrated cover as defined in claim 1 wherein said thermoformed cover is a vacuum thermoformed cover.
 7. The integrated cover as defined in claim 1 wherein the thermoformed cover is a pressure thermoformed cover.
 8. The integrated cover as defined in claim 1 wherein the thermoformed cover has a size and shape generally conforming to the size and shape of the body element.
 9. The integrated cover as defined in claim 8 wherein said thermoformed cover has an exterior face surface and a suitable window area defined in at least a portion of said exterior face surface for viewing the visible display of information shown on a screen constructed in at least a portion of the body element.
 10. The integrated cover as defined in claim 9 further comprising a border outline silk screen printed on said exterior face surface around said window area.
 11. The integrated cover as defined in claim 9 further comprising at least one pattern silk screen printed on said exterior face surface.
 12. The integrated cover as defined in claim 1 further comprising indicia silk screen printed on said exterior face surface at one or more locations corresponding to a desired predetermined functionality associated with the electronic device.
 13. The integrated cover as defined in claim 1 wherein said thermoplastic sheet further includes keymat functionality.
 14. The integrated cover as defined in claim 13 wherein said thermoplastic sheet further includes an adapter plug for electrically connecting said integrated keymat to the electronic circuitry carried by the body element.
 15. The integrated cover as defined in claim 1 wherein said electronic device further comprises a portable electronic device.
 16. The integrated cover as defined in claim 1 wherein said electronic device further comprises a mobile telephone.
 17. Method, comprising: providing an integrated cover for an electronic device having at least one body element further comprising: providing a thermoplastic sheet; providing a suitable mold arranged to substantially correspond to the desired cover for the electronic device; heating the thermoplastic sheet to a suitable temperature; conforming at least a portion of the heated thermoplastic sheet to the mold; and cooling and removing the thermoplastic sheet from the mold, whereby a thermoformed cover corresponding to said desired cover for the electronic device is formed in said at least one portion of the thermoplastic sheet.
 18. The method as defined in claim 17 further providing a thermoplastic sheet having characteristics and properties to accommodate the mechanical requirements of the cover for the electronic device.
 19. The method as defined in claim 17 further including separating the thermoformed cover away from the thermoplastic sheet.
 20. The method as defined in claim 17 further including conforming by vacuum to draw the heated thermoplastic sheet against the mold to form the thermoformed cover.
 21. The method as defined in claim 17 further including conforming by pressure to press the heated thermoplastic sheet against the mold to form the thermoformed cover.
 22. The method as defined in claim 17 further providing a thermoplastic sheet with keymat functionality.
 23. The method as defined in claim 22 further providing a thermoplastic sheet having an adapter plug for electrically connecting the integrated keymat to the electrical circuitry of the electronic device.
 24. The method as defined in claim 17 further including silk screen printing on the exterior facing surface of the thermoplastic sheet corresponding to the outward facing surface of the thermoformed cover at least one of desired text, graphics, patterns, and window outline borders, whereby the silk screen printed text, graphics, patterns and window outline border appears on the exterior outward facing surface of the thermoformed cover. 